Method of producing solid bodies from powder or other loose material.



J. A. WILLIAMS.

METHOD OF PRODUCING SOLID BODIES FROM POWDER OR OTHER LOOSE'MATERIAL.

APPLICATION FILED JULYII; I9I5.

1 174,646. Pat el lted Mar; 7,1916.

I I r UNITED STATES PATENT oEEIoE.

JOSEPH A. WILLIAMS, 0]? CLEVELAND, OHIO.

METHOD OF PRODUCING SOLID BODIES FROM POWDER OR OTHER LOOSE MATERIAL.

Specification of Letters Patent.

Patented Mar. '7, 1916..

Application filed July 14, 1915. Serial No. 39,785.

To all whom it may concern:

Be it known that I, JOSEPH A. WILLIAMS, a citizen of the United States, residing at Cleveland, in the county of Cuyahoga and State of Ohio, have invented a certain new and useful Improvement in Methods of Producing Solid Bodies from Powder or other Loose Material, of which the following is a full, clear, and exact description.

This invention relates to certain improvements in the process of producing solid bodies wherein finely divided material or material in the form of powder is compressed into a bar, brick or ingot, and has for its object the tun gsten,such as tungsten wire for use as lamp filaments and for other purposes,tungsten in the form of powder or loose crystals is compressed generally by means of a hydraulic press into a brick or ingot which for convenience will be termed a bar. This bar is then heated in an atmosphere of hydrogen to partly sinter it. Then the bar is placed in a so-called treating bottle and heavy current is passed through it in the presence of hydrogen, this being continued until the bar is heated almost to a molten state. In this step of the process the bar shrinks very perceptibly in volume. Then the bar is reduced to the form of rod or wire by repeatedly swaging and heating. The rod or wire thus formed is ductile and is used for numerous purposes, but is generally drawn through diamond dies to form fine wire lamp fila ments.

' I have found that the density of the finished product, and certain other characteristics or properties are affected or limited by the density of the bar which is produced by subjecting the powdered tungsten to pressure. Heretofore the powdered tungsten been found unfeasible to employ tungsten powder having more than a certain degree of fineness, and also to the fact that the pressure to which the powder could be subjected 1n forming a brick or ingot is limited. It the powder is subjected to more than a predetermined pressure in the press, the brick Wlll split or cleave and is thereby rendered useless.

By my invention I am enabled to use a finer powder, and am also able to subject the powder to reater pressure than was heretofore possi 1e. By way of explanation it may be stated that I have found that with the process carried on heretofore a finer powderand also a greater pressure could not be employed successfully because of the presence of air in the mass of powder between the particles or crystals composing the bar. I have not been able to ascertain definitely why this is true, but I believe that the fine grains of powder, 2'. 6., the powder finer than that heretofore employed successfully, could not be employed because the air can not readily escape-while the powder is being compressed to form the bar, and I believe also that the cleaving of the bar when excessive pressure is employed is due also to the presence of air,possibly the expansion of air when the pressure is removed.

In carrying out my invention I remove air from the powder or from the bar being compressed and am thereby enabled to employ finer powder and greater pressure than heretofore, and preferably this is accomplished by compressing the powder in a vacuum or partial vacuum which for convenience will be termed in nae a0, 2'. 6., in a chamber from which as much of the air is removed as is practically possible.

Although the step of the process can be carried out in numerous different ways, and with many different kinds of apparatus, in the accompanying sheet of drawings I have shown one way of accomplishing the result. and in the drawings Figure 1 is a side View of a hydraulic press equipped with an attachment by which the powder or finely divided material can be compressed in a vacuum; and Fig. 2 is a horizontally sectional view substantially along the line 2-2 of Fig. 1.

The device shown in the drawings consists of a hydraulic press, including an upper stationary head 10, a Vertically movable table or plunger 11 having a piston extending down into a hydraulic cylinder 12 to which water under great pressure may be supplied as is common in presses of this type. The upwardly moving plunger'12 is providedon the top with a mold 13 having a recess 1-1 which receives the powdered tungsten or other finely divided material and in which the bar is formed. The size and dimensions of the recess of the mold'can be varied and will depend upon the dimensions of the bar which is to be formed. The powder is compressed in the mold into the formof bar by a die 16 which is held up against a filler block 17 attached to the head 10, by means of coil springs 18 guided and supported by vertical rods extending between the head of the die and the top of the mold.

I provide around the mold a vacuum chamber, and preferably this chamber is composed of upper and lower telescopic cyl-' inders 19 and 20 carried by the head 10 and plunger 11, respectively, and completely surrounding or inclosing the die, mold and tungsten or other material being compressed when the plunger iselevated to compress the material. The vacuum is formed in the chamber by sucking or withdrawing the air therefrom by means of a suitable suction pipe 21 which will be connected to an ordinary suction or vacuum pump not shown. It will be understood, of course, that any suitable means may be provided for forming air tight joints between the telescoping parts of the cylinders and at other points, such as points of attachment of the cylinder sections with the head and plunger of the press.

Before the powder is compressed the air is withdrawn, forming a vacuum in and around the finely divided material, die and mold, the pump being set in operation so as to form the vacuum not only prior to the compression of the material but also during the interval that the material is being compressed, which is usually several minutes. By thus removing the air from the material being compressed a much finer powder or a more finely divided material can be utilized and much greater pressure can be applied than was heretofore possible, and in consequence a very much denser bar can be obtained. If tungsten is being produced, after the bar is formed as above described, it is then subjected to the sintering process, swaging and heating, and there is obtained a solid metal denser than that obtained heretofore and one having properties more suitable for many uses.

The springs 18 are employed to hold the die from the material being compressed until the air' is removed. It is very important that the vacuum be produced in the chamber before any considerable pressure is created on the material for otherwise the in the manner above explained will depend somewhat upon the materials being operated on. In the production of tungsten the pressure will be as great .as the die and mold will stand, which will be between thirty and forty tons per square inch.

After the brick or ingot is formed by the method above described, precisely the same steps may be employed as are now employed to form the solid ductile tungsten from the 2 bar, or any other steps which will produce the desired results may be carried out, the essential feature of my process being the removing of air or other gas from the finely divided material or. from the bar before and while the material is being compressed, regardless of the particular steps if any which are subsequently carried out, and regardless of the particular material being operated on.

Having thus described my invention what I claim is 1. The method of forming a bar Which comprises removing air from a quantity of finely divided material and subjecting the material to pressure.

2. A step in the process of forming a solid body which comprises compressing a quantity of finely divided material in 'vacuo.

3. A step in the method herein described, which comprises treating powdered material so as to form a bar in the absence of air.

4. The method of forming a bar from material in finely divided form, which comprises first removing air from a quantity of material and then subjecting the material to pressure.

5. The method of forming solid metal tungsten from tungsten in finely divided form, which comprises withdrawing air from a quantity of the finely divided tungsten and subjecting the same to pressure.

6. The method of forming solid metal tungsten, which comprises compressing a quantity of tungsten in powdered form in rmruo so as to form a bar and then heating the bar and swaging the same.

In testimony whereof, I hereunto afiix my signature.

JOSEPH A. \VILLIAMS. 

